CHAPTER 62 LOW CEREBROSPINAL FLUID HEADACHE

BACKGROUND AND TERMINOLOGY

In 1938, Schaltenbrand used the term aliquorrhea to describe the spontaneous occurrence of an entity manifested by very low cerebrospinal fluid (CSF) opening pressures and orthostatic headaches, among other features.^1,² Sometimes referred to as Schaltenbrand’s headaches, this later came to be known as spontaneous intracranial hypotension.³ It is now realized that practically all cases of spontaneous intracranial hypotension result from spontaneous CSF leaks,⁴ often at the level of the spine (particularly the thoracic spine⁵) and only rarely at the skull base. CSF leak leads to CSF volume depletion. Terms such as spontaneous CSF leak, CSF hypovolemia, and CSF volume depletion have been used interchangeably with spontaneous intracranial hypotension, because some patients with this disorder have consistently normal CSF opening pressures.^5,⁶ True hypovolemic state (reduced total body water), CSF shunt overdrainage, dural holes or tears as the result of lumbar puncture, epidural catheterization, surgery, and trauma all may lead to loss of CSF volume. In this chapter, we focus on spontaneous CSF leaks.

ETIOLOGY OF SPONTANEOUS CEREBROSPINAL FLUID LEAKS

The cause of spontaneous CSF leaks often remains undetermined, but two etiologic factors should be considered: trivial trauma and weakness of the dural sac.

Some patients report a history of trivial trauma, such as coughing, pushing, trivial falls, lifting, and sports activities. Evidence for weakness of the dural sac is accumulating. Meningeal diverticula are seen more frequently in patients with spontaneous CSF leaks. Increased frequency of meningeal diverticula and also CSF leaks have been reported in Marfan’s syndrome.⁷^–⁹ Some patients with spontaneous CSF leaks show stigmata of the disorders of a connective tissue matrix (e.g., marfanoid features, hyperflexible joints, hyperextensible skin).^5,¹⁰

In uncommon instances, a dural tear from a spondylotic spur or disc herniation ^11,¹² may cause dural defect and CSF leak.

CLINICAL MANIFESTATIONS

Headache is the most common manifestation. It is “classically” orthostatic (present in upright position, relieved by recumbency).^3,⁵ It is often not throbbing, but it may be throbbing; it is often bilateral, but it may be unilateral; and it is often aggravated or sometimes even triggered by Valsalva-type maneuvers. The headache may be frontal, fronto-occipital, holocephalic, or occipital. Not all headaches in CSF leaks are orthostatic, and variability is substantial (Table 62-1).^5,¹³^–¹⁷ Furthermore, not all orthostatic headaches result from CSF leaks. For example, they can be the dominant clinical manifestation in some patients with postural tachycardia syndrome.¹⁸

TABLE 62-1 Headache Variations in Cerebrospinal Fluid (CSF) Leaks

Orthostatic headaches may be preceded by neck pain or interscapular pain or both or by lingering nonorthostatic headaches.

With chronicity, sometimes the orthostatic features may dampen and the headache may be transformed into chronic lingering headaches that are present even in recumbency.⁵

Sometimes the headaches may have an acute thunderclap-like onset mimicking a subarachnoid hemorrhage ¹³ before orthostatic features are recognized.

In rare cases, a paradoxical postural headache (headache present in recumbency, relieved in upright position) may occur.¹⁴

Sometimes a second-half-of-the-day headache may occur. Typically, patients are headache free in the morning, but by later morning or early afternoon, they develop a headache that would increase in severity if the patients continued to be up and about; the headaches decrease clearly or vaguely in recumbency.¹⁵

Exertional headaches occur in isolation or are accompanied by some of the other clinical manifestations of CSF leaks and without any orthostatic features.¹⁶

With intermittent CSF leaks, the headaches may appear and disappear for variable periods of time.

Sometimes patients with documented CSF leaks and low CSF pressures and typical MRI abnormalities may have no headache at all—the acephalgic form.¹⁸

MRI, magnetic resonance imaging.

CLINICAL MANIFESTATIONS OTHER THAN HEADACHES

Many of the patients with spontaneous CSF leaks have one or, often, more symptoms in addition to the headaches (Table 62-2).^3,^5,¹⁹^–³²

TABLE 62-2 Clinical Features Other Than Headaches

Interscapular or neck pain (sometimes orthostatic), low back pain

Nausea, sometimes emesis, often orthostatic

Horizontal diplopia (unilateral or bilateral sixth cranial nerve palsy)¹⁹

Cochleovestibular manifestations (dizziness, change in hearing, tinnitus)^3,^5,²⁰

Photophobia, visual blurring

Upper limb numbness or pain ⁵

Rare manifestations: facial numbness or weakness, diplopia due to third or fourth cranial nerve palsy,²⁰^–²³ galactorrhea,²⁴ Menière’s disease–like manifestations,²⁵ upper limb radiculopathy,²⁶ encephalopathy,²⁷ stupor,²⁸ coma,²⁹ parkinsonism,³⁰ ataxia, incontinence, gait unsteadiness,³¹ frontotemporal dementia³²

Proposed mechanisms of clinical manifestations in CSF leaks and intracranial hypotension are listed in Table 62-3.^3,^5,¹⁹^–³⁴

TABLE 62-3 Mechanisms of Clinical Manifestations or Cerebrospinal Fluid Volume Depletion

Clinical Manifestation	Proposed Mechanism
Headache	Descent of the brain, stretch and distortion of pain-sensitive suspending structures of the brain^3,^5,^33,^34,^34a
Cranial nerve palsies	Stretching or compression of related cranial nerves¹⁹^–²³
Dizziness, change in hearing	Stretching of eighth cranial nerve or pressure changes in perilymphatic fluid of the inner ear^5,²⁵
Galactorrhea and increased prolactin	Distortion of pituitary stalk²⁴
Radicular upper limb symptoms	Stretching of cervical nerve roots or irritation by dilated epidural venous plexus^5,²⁶
Encephalopathy, stupor, coma	Diencephalic compression²⁷^–²⁹
Cerebellar ataxia, parkinsonism	Compression of posterior fossa and deep midline structures³⁰
Frontotemporal dementia	Compression of frontotemporal lobes³²
Gait disorder	Spinal cord venous congestion³¹